One man was killed and his brother was seriously wounded in a Southeast Washington housing development last night after a man with a handgun stood them against a wall and shot them at close range.

After reloading, the gunman reportedly fired at other persons in a courtyard in the development and shortly afterward shot a man riding a bicycle on a nearby street.

Police said they believed robbery was a possible motive in the first two shootings, which occurred about 7:30 p.m. in the Potomac Gardens development at 13th and I streets SE, about one mile southeast of the Capitol.

Officers combed the area for hours as a police helicopter flew overhead but the gunman and an accomplice remained at large early today.

Some residents of the area told the police they believed that the gunman might have known the first two men he shot, but this could not be confirmed. Police and witnesses said the third victim apparently was chosen at random as he pedaled his bicycle on K Street SE near the intersection at 13th Street.

The man who was killed was identified last night at D.C. General Hospital as Lonnie Huff, 27, of 1930 I St. NE. He was pronounced dead at the hospital at 8:25 p.m.

The second man shot inside the development was identified as Andrew Huff, 38, of 4015 Fourth St. NW, and was described as Lonnie Huff's brother. Andrew Huff was recuperating at the hospital this morning after surgery for his wounds.

"I guess they both were just caught up at the wrong place at the wrong time," said a third brother, Larry Huff, 28.

He said his slain brother was a presser in a dry cleaners and that he wrote songs and aspired to be a professional musician.

He said he was told that his brother, who seemed always to smile, had been laughing just moments before he was shot.

The third victim, identified as Riley Hickson, 20, of 2804 N St. SE, was reported in stable condition at the hospital

The courtyard area where the first two men were shot is poorly lighted, paved and surrounded by three-story brick buildings that shield it from street view. According to police and neighbors, drug trafficking has been reported in the area.

Witnesses told police that the gunman, described as a tall man, and his accomplice, described as a shorter man, confronted the Huff brothers in the courtyard and forced them to stand against one of the brick walls of the development.

The dead man was shot in the heart; his brother was shot twice, a hospital official said.

As both slumped to the ground, the gunman reloaded, walked a few steps away and began firing at persons gathered in a walkway. Then, after firing a final shot into the air, he and his accomplice left.

One of the men gathered near the walkway told a reporter later that he had heard gunfire before witnessing anything. Then, said the man, "I saw this guy shooting in our direction.

"It seemed like after he had shot the first two guys he started shooting at any and everybody.

"Everybody was running," the witness said. "There was mass confusion. After I saw him shooting directly at us, I just took off running."

Another witness said he saw the gunman and his accomplice walk deliberately from the courtyard, pause on 13th Street SE, possibly to reload the gun, and then walk on.

Shortly afterward, police said, Hickson was shot in the buttock and abdomen as he rode his 10-speed bicycle west on K Street SE, about one block from the housing development.